A Bookmark refers to a location in the document and has a unique name, which identifies it. Every Bookmark has a corresponding BookmarkRangeStart and BookmarkRangeEnd, which are inline elements. These two elements specify the Bookmark's location as follows:

[C#] Example 1: Add а bookmark to а paragraph

Note, that the paragraph should belong to the same document that is passed to the constructor of the Bookmark object, otherwise an exception is thrown. The bookmark's location is specified around a run with text "text".

Inserting a Bookmark in the document can also be done with the RadFlowDocumentEditor class like shown in Example 2: